Alteration in the plasma testosterone: estradiol ratio: an alternative to the inhibin hypothesis.
The data suggest that in the absence of the testis: (1) testosterone can maintain both FSH and LH concentrations chronically within the physiological range; (2) that estradiol preferentially suppresses plasma LH concentration, indicating that the androgenic component of testosterone modulates FSH secretion; and (3) that subphysiological testosterone concentrations accompanied by physiological estradiol levels permit FSH to escape to midcastrate levels while maintaining LH concentration at intact levels. An alteration in the testosterone: estradiol ratio can account for a selective FSH elevation when testosterone production is low. The data provide an alternative explanation for the inhibin phenomenon.
D000818:Animals; D002369:Castration; D004305:Dose-Response Relationship, Drug; D004958:Estradiol / Q000097:blood* / Q000494:pharmacology; D005640:Follicle Stimulating Hormone / Q000097:blood*; D007031:Hypothalamus / Q000032:analysis; D007265:Inhibins; D007986:Luteinizing Hormone / Q000097:blood*; D008297:Male; D010906:Pituitary Hormone-Releasing Hormones / Q000032:analysis; D011506:Proteins / Q000502:physiology*; D051381:Rats; D013735:Testicular Hormones / Q000502:physiology*; D013739:Testosterone / Q000097:blood* / Q000494:pharmacology
D010906:Pituitary Hormone-Releasing Hormones; D011506:Proteins; D013735:Testicular Hormones; D013739:Testosterone; D004958:Estradiol; D007265:Inhibins; D007986:Luteinizing Hormone; D005640:Follicle Stimulating Hormone